A reduced fastener model using Multi-Connected Rigid Surfaces for the prediction of both local stress field and load distribution between fasteners

• A finite element model of bolt is proposed to reduce time calculation of fastened joints.
• Different deformation modes of bolt are analysed to justify model construction.
• The bolt is represented by rigid surfaces linked with elastic connectors.
• The proposed model provide high-precision load distribution and local stress field.

This paper describes the development of a reduced model of a fastener using Multi-Connected Rigid Surfaces (MCRS). The stiffness of the connectors is determined, based on a physical approach, considering different deformation modes of the bolt. The reduced model is constructed and identified from a numerical simulation of a single lap reference joint under tensile load, with the adherent parts and bolts represented by 3-D solid elements. A single simulation with a given clearance, axial preload and friction coefficient is used to identify equivalent stiffnesses. The reduced model is then compared with the 3-D solid elements model in a two-fastener configuration for different values of clearance, preload and friction coefficient. The comparison covers overall response in terms of stiffness and load distribution between fasteners, local response in terms of stress fields and calculation times. Results show that the reduced model proposed here is able to reduce calculation times while still providing a good estimate of the mechanical quantities needed for the study and dimensioning of multi-fastener joints.